This invention relates to the production of epoxy resins. In one aspect, the invention relates to the production of low-chlorine diglycidyl ether of biphenols suitable for electronics applications.
Epoxy resins are used in the electronics industry for encapsulating semiconductors and other sensitive electronic parts. Encapsulation formulations typically contain an epoxy resin, a curing agent and a filler material such as silica. In the encapsulation process, the electronic part is cast with a molten encapsulation formulation which is then subjected to conditions effective to cure the epoxy resin. The resulting cured resin provides physical integrity and environmental protection for the encapsulated part.
The epoxy resin used in encapsulation formulations must meet a demanding set of criteria, including low melt viscosity and low chlorine content. Diglycidyl ethers of biphenols, such as the reaction products of epichlorohydrin and biphenols, for example, have low melt viscosity and are useful in encapsulation, but these resins typically have residual chlorine levels in excess of 1000 ppm. This residual chlorine can, particularly at the high-temperature conditions which exist in current high-performance electronic systems, corrode metal parts of the underlying electronic component and will cause eventual failure of the part.
It is therefore an object of the invention to provide a process for preparing epoxy resins. In one aspect, it is an object of the invention to prepare low-chlorine epoxy resins suitable for high-performance electronics applications.